           (println :curr-world @curr-world)
           (<! prog-ch)
           (close! event-ch)
+          (close! render-ch)
           (recur (inc num-worlds)))))))
 
 ; --------------------------------------------

                                 }}
                  :chs {} ; {ch -> {:id (gen-id), :msgs {msg -> true},
                          ;         :first-taker-actx actx-or-nil}}.
                  :gen-id gen-id})]
        (reset! curr-world {:world world
                            :net-listen-ch (achan-buf world 10)
                            :net-connect-ch (achan-buf world 10)
                            :servers {}
                            :clients {}})
        (cbfg.vis/process-events vis event-delay event-ch step-ch render-ch)
        (make-net world
                  (:net-listen-ch @curr-world)
                  (:net-connect-ch @curr-world))

(defn world-vis-init [el-prefix init-event-delay]
  (init-roots)
  (let [prog-ch (listen-el (gdom/getElement "prog-go") "click")
        step-ch (chan (dropping-buffer 1))]
    (go-loop [num-worlds 0]
      (let [last-id (atom 0)
            gen-id #(swap! last-id inc)
